The invention relates to an exhaust gas aftertreatment device for a combustion engine, in particular of a motor vehicle.
Such an exhaust gas aftertreatment device for a combustion engine, in particular of a motor vehicle, can be found in U.S. 2010/0212292 A1. The exhaust gas aftertreatment device includes at least one exhaust pipe element having an exhaust duct through which exhaust gas of the combustion engine can flow. Moreover, the exhaust gas aftertreatment device includes a dosage device which opens into the exhaust duct at a feed point. The dosage device is configured to introduce a reduction agent which is also referred to as a reducing agent into the exhaust pipe element at the feed point. For example, the reduction agent is urea which is present in an aqueous urea solution. Usually, the reduction agent is stored in a tank of the motor vehicle and carried along in the tank.
The exhaust gas and the reduction agent contained in the exhaust gas flow to an SCR catalytic converter (SCR—Selective Catalytic Reduction) by means of which a reaction of the exhaust gas and in particular of nitrogen oxides (NOx) contained in the exhaust gas with ammoniac (NH3) contained in the reduction agent is caused. In the course of this reaction the ammoniac reacts with the nitrogen oxides to produce water and nitrogen. Thus, the reduction agent is used for the so-called denitriding of the exhaust gas.
Furthermore, DE 10 2011 051 875 A1 shows a dosing module for an exhaust gas aftertreatment system of a vehicle, the dosing module being used to inject a reducing agent along a flow of exhaust gas at a front side of an SCR catalytic converter.
It has been shown that a significant urea deposit, in particular on the exhaust pipe element, can occur, wherein the urea deposit cannot be used for the selective catalytic reduction.
Therefore, it is an object of the present invention to provide an exhaust gas aftertreatment device of the aforementioned kind, in which the urea deposit can be kept particularly low.
In order to provide an exhaust gas aftertreatment device in which an exhaust gas aftertreatment device urea deposit can be avoided or can be kept particularly low, according to the present invention the exhaust gas aftertreatment device includes a baffle which is arranged in the exhaust duct. By means of the baffle the exhaust duct is at least partially divided into two passages which have an inlet opening for the exhaust gas respectively so that the exhaust gas can flow through the passages. The passages are fluidically arranged in parallel. This means the passages are not arranged in sequence so that the exhaust gas does not need to flow through one of the passages at first and then through the other passage, but the exhaust gas can flow simultaneously or fluidically parallel through both passages. Thus, a main flow of the exhaust gas is divided into two partial flows by means of the baffle, where one of the partial flows flows through one of the passages and the other partial flow flows through the other passage, in particular in a parallel manner.
The feed point of the reduction agent for the exhaust gas aftertreatment device according to the present invention is arranged in one of the passages and shielded from the other passage by the baffle, where at least the inlet opening of the other passage is arranged upstream of the feed point. Thus, the one passage is a mixing passage in which the reduction agent is mixed with the exhaust gas flowing through one passage. Hence, the reduction agent, in particular urea, can deposit on the baffle, in particular on an inner surface of the baffle, bounding the one passage at least partially. However, the other passage can be used as a heating passage which starts from a location before the feed point and a mixing zone in which the reduction agent is mixed with exhaust gas since the inlet opening of the other passage is arranged upstream of the feed point. Thereby, it can be ensured that the exhaust gas flowing through the other passage (heating passage) is always free of reduction agent and, thus, deposit, thereby effectively heating the deposit and deposit sites on the baffle all the time. Thereby, deposit on the baffle can be resolved and/or kept particularly low. Thus, the consumption of the reduction agent during the operation of the combustion engine can be kept particularly low. Moreover, repair cost resulting from urea deposit can be reduced or avoided.
The baffle can be implemented in existing exhaust gas aftertreatment devices with little changes at the most so that the costs for retrofitting existing exhaust gas aftertreatment devices can be kept low. Since the deposit of the reduction agent can be avoided or kept particularly low, a less frequent regeneration is needed which results in a reduced fuel consumption of the combustion engine.
In a particularly advantageous embodiment of the invention, the baffle is configured as an entirely closed dividing wall. This means the baffle does not have any through openings through which exhaust gas or reduction agent can flow. Thereby, the other passage can be shielded from reduction agent particular effectively so that reduction agent deposit can be kept particularly low, especially on the inner surface of the baffle since the baffle can be heated by the exhaust gas flowing through the passage very efficiently.
It has turned out to be particularly advantageous if the baffle has at least one curved portion for diverting or deflecting the exhaust gas. Thereby, a particularly advantageous flow of the exhaust gas can be realized so that reduction agent deposit can be kept particularly low. Moreover, by diverting or deflecting the exhaust gas, the back pressure caused by the exhaust gas aftertreatment device can be kept very low.
In a further particularly advantageous embodiment of the invention, the baffle has at least one straight portion extending parallel to the direction of flow of the exhaust gas, the straight portion being arranged upstream of the curved portion. By means of the straight portion, the exhaust gas can be guided advantageously to the curved portion which diverts or deflects the exhaust gas after the straight portion. Hence, a particularly efficient operation of the exhaust gas aftertreatment device can be realized.
For realizing a particularly advantageous flow of the exhaust gas, the baffle has at least one end portion which is bent to one of the passages, in particular towards the one passage, with respect to at least one other portion of the baffle. Thereby, for example, the main flow of the exhaust gas can be split into the partial flows in a need-based manner so that reduction agent deposit can be kept particularly low.
In order to keep the backpressure caused by the exhaust gas aftertreatment device particularly low, the baffle can be streamlined.
The invention further relates to a motor vehicle including a combustion engine and at least one exhaust gas aftertreatment device according to the present invention. Advantageous embodiments of the exhaust gas aftertreatment device according to the present invention are to be regarded as advantageous embodiments of the motor vehicle according to the present invention and vice versa.
Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respective indicated combination but also in any other combination or taken alone without leaving the scope of the invention.